4.6 sohc question?

Discussion in '96-04 - 2V Specific' started by s3c2n01, Apr 10, 2007.

  1. s3c2n01

    s3c2n01 New Member

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    I have a 98 gt npi. i swapped the cams for the pi and slammed the pistons on the pass side. with the exhaust valves.

    so here is my problem.
    i have 03 cobra pistons and 5140 i beam rods and 03 cobra crank. i was wandering if anyone knows what the compression would be with pi heads.
    i know with stock pistons and pi heads it jumps to 10.5.1 i am running vortech s- trim 6-8 lbs with Anderson Ford power pipe will add 2 or 3 more pounds of boost.

    or where i can find out the info.

    thanks chris
     
  2. Thomas_W

    Thomas_W Well-Known Member

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    imma go out on a limb and say upper 9's lower 10's w/o knowing right off the top of my head the piston dish size..... whats the dish size of those pistons?
     
  3. s3c2n01

    s3c2n01 New Member

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    not 100% sure. i think the stock pistons in the 03 cobra on the manley website is 18cc.
     
  4. ripper

    ripper Well-Known Member

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    I have forged probes and mine are 18cc. On the pi motor my comp is 9:1. Are you gonna do h/c/i along with the r/a? Also i thought pi cams would clear flathead pistons on a non pi motor :dunno:
     
  5. voidfinger

    voidfinger Well-Known Member

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    they do, timing must have been way way off.

    Many people do the head and cam swap and have no problems at all, there is a good amount of room to go.
    Did the timing marks read right?
     
  6. ripper

    ripper Well-Known Member

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    Thats what i thought. Maybe he stretched a piston or rod.
     
  7. s3c2n01

    s3c2n01 New Member

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    i had the timing was off. i have had someone from blackmustangclub.com tell me it should be around low 9 or mid 9.

    i am off to rebuild my motor for the s trim and gas . wish me luck i will keep every one posted on this.


    thanks for the info guys.
     
  8. s3c2n01

    s3c2n01 New Member

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    pi cams in npi heads. i am trying to see if it would be safe for pi heads on a npi motor with 03 cobra pistons and s trim and power pipe.
    without out pulling a butt load of timing and not running race gas all the time. daily driver for now